sarahp, your problem is a very common one, especially in newly set up ponds. The biofilter has not had time to mature any beneficial bacteria, in ponds it can take a few months depending on the weather. There are two things you might try. You don't tell me what type of algae you have, nevertheless try some specially prepared barley straw from outdoor aquatic centres. You tell me that your water is discoloured. Depending on the colour will depend on treatment. Green away to destroy algae will make the matter worse. The reason the water is green(if it's green) is there is a lot of algae suspension and green away will only compound the situation. Worst senerio would be that the green turns brown and pollute your pond. You need to understand the cycle of a plant,after all algae are plants, then you can eradicate it. However if you are determined that you want a quick fix, then add a seperate UV system into the pond. As the algae is passed through the UV light, it gets sterelized. however a word of warning here, you may be ridding the pond of greenwater, but the cause still exists. I hope this has been of some assistance.